Electrical measuring instrument.



Patented Apr, 29, I902.

T. DUNCAN. ELECTRICAL MEASURING INSTRUMENT. (Application filed Jan. 2, 19004 Renewed Jan. 6, 1902.) (No Model.)- 2 Sheets-Sheet I.

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No. 698,685. Patented Apr. 29, I902.

T. DUNCAN. ELECTRICAL MEASURING INSTRUMENT. (Application filed Jan. 2, 19 00. Renewed Jan 6, 1902.)

2 Sheets-Sheejt 2.

(No Model.)

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THOMAS DUNCAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SIEMENS & IIALSKE ELECTRIC COMPANY OF AMERICA, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

ELECTRICAL MEASURING INSTRUMENT.

SPECIFICATION forming part/of Letters Patent N 0. 698,685, dated April 29,1902.

Application filed January 2, 1900. Renewed January 6, 1902. Serial No. 88,492. (No model.)

To all whom, it may concern.-

Be'it known that I, THOMAS DUNCAN, a citizen of the United States, residing at Chicago,

in the county of Cook and State of Illinois,

.of a system of distribution, my invention enabling me to accurately secure this result.

Then the pressure at any point distant from the generating-station is accurately determined, this pressure may be maintained constant by regulation of the impressed pressure to compensate for load changes and the C R drop over the distributing-lines due thereto, which varies directly as the load. A method heretofore frequently employed for measuring the impressed pressure at points distant from a generating-station in both alternating and direct current systems of distribution consisted in extending two pressure-wires from the distant point to the generating-station and there connecting the same with a voltmeter. When the distance to the distant predetermined point is great, the expense of these pressure-wires is significant when a great number of machines are used.

In measuring the potential at distant points,

in direct-current systems of distribution it has also been the practice to employ what are termed compound compensating volt meters containing two windings, one a pressure-winding connected between the generator-terminals and the other a counter compounding or demagnetizing winding comprising one or more turns of the series or main conductor upon the same voltmeter-spool with the shunt-winding, the current increasing the counter magnetizing effect of the series winding as the load increases to give a resultant magnetizing eifect, which indicates the pressure reduction in the transmissionlines. The number of turns of the current or series winding is dependent upon the percentage of drop in the mains. been the practice in measuring potential at distant points from a generating-station in alternating-current systems of distribution toemploy a voltmeter connected in circuit with the secondary coils of transformers whose primaries are respectively included in series with a main transmission-line and between the transmission-lines. These latter methods, however, are objectionable, since a true compensation is not always efiected in the meter for the C R drop, since the effect of the series winding in either case would be the same irrespective of the distance of the load from the generator.

By means of my present invention I am enabled to eliminate one or both of the pressure wires employed in one of the aforesaid prior methods, to reduce theco'st of line construction, and at the sametime maintain accuracy in the determination of the pressure at the distant point of distribution where the pressure is to be measured. I am also enabled to overcome the disadvantages of the latter two aforesaid prior methods of'determining the It has also pressure at points distant from the generating-station in thatl am enabled to accurately determine this pressure irrespective of the distribution of the load.

In applications Serial Nos. 87, SS, 89, 90, 91, and 92, filed of-even date herewith, I have set forth measuring apparatus for accomplishing the measurement of pressure at points dis tant from the generating-stations. In practicing the inventions set forth in the said copending applications I have included a winding of the meter in a pressure-conductor in shunt of one side of a transmission-line or a portion thereof. In practicing my present invention I include one of the meter-coils in bridge between the sides of the transmissioncircuit, one connection of the said winding being effected at the generating-station-with one side of the transmission circuit, While the other connection is effected at thedistant point where the pressure is to be determined with the other side of the transmission-circuit.

The remaining coil of the meter is connected at the generating-station between the generator-terminals. By a proper calibration of the measuring apparatus the windings thereof will jointly serve to determine the pressure at the distant point.

I will explain my invention more fully by reference to the accompanying drawings, in which- Figure 1 illustrates a system of direct-current distribution with a measuring apparatus connected in circuit therewith in accordance with the invention. Fig. 2 illustrates a system of alternating-current distribution with a measuring apparatus connected in circuit therewith in accordance with the invention.

Referring now more particularly to Fig. 1, I have shown a source of direct current 1 supplyingcurrent to translating devices 2. The instrument 3 may be constructed as shown, two field-poles 4 5, of soft iron, being preferably provided, a permanent horseshoe-magnet 6 being preferably employed, upon the ends of which said pole-pieces are secured. An iron core 7, which is preferably stationary, is disposed between the poles. A coil 8 of fine wire, mounted upon a rotatable shaft, surrounds the iron core and is disposed between the pole-pieces, this coil being included in circuit between the generator-terminals, a resistance 9, extraneous to the said coil, being included in the same cross-conductor therewith to prevent waste of current through the said coil. Atorque is thus produced proportional to the pressure impressed by the generator upon the transmission-mains. Torsional springs may be provided in the wellknown way to oppose the torques of the instru ment. 1 have shown a pointer 10, mounted to swing with the coil, and a scale 11, upon which the measurements may be read. A second coil 12 is mechanically coupled with the aforesaid coil, the latter coil being preferably mounted upon the same shaft with the coil 8. A coil 12 may be included in bridge between the transmission-mains, in this instance between the separated points 13 and 14 at the generator and at a distant point of the transmission system, respectively, an extraneous resistance 15 being preferably adapted for inclusion in the same circuit with the said coil. I have shown a metallic conductor 16 for connecting the points 13 and 14:. A part of this pressure-conductor may be replaced by the ground connections 17. The point 14 maybe at the center of distribution, at the extreme end of the system of distribution, at a point between the extreme end and the center of distribution, or at any other point distant from the generating-station.

In Fig. 2 an alternating-current generator 18 is shown as supplying current to translating devices 19. The instrument 20 may be constructed as shown. The winding of the meter interposed between the generator-terminals is shown as being divided into a stationary field-coil 21 and the revoluble coil 22.

The winding interposed between a point near the generator and a distant point of the transmission-line is divided into a stationary fieldcoil 23 and the revoluble coil 24. The revoluble coils are preferably jointly subjected to the action of each of the fixed coils.

In order to adapt the instrument to the measurement of voltages in alternating-current systems of electrical distribution, the coils thereof are unprovided with iron cores.

A pointer 10 moves with the revoluble coil,

a scale 11 being provided upon which the pointer may indicate measurements. The coils 21 and 22 are preferably included in series, as are also the coils 23 and 24; but I do not wish to be limited to this series arrangement. A resistance 9, extraneous to the winding composed of the coils 21 and 22, is provided to prevent waste of current, a resistance 15 for like purpose being also included in series with the winding composed of the coils 23 and 24. Torsional springs may be provided in the well-known way to oppose the torques of the instrument shown in Fig. 2.

In Fig. 2 I have shown a system of alternatingcurrent distribution of high electromotive force, and instead of connecting the .windings of the meter directly between the mains of the system and the conductor interposed between a point of the transmissioncireuit 13 near the generator and a distant point 14 I employ transformers 25 and 26, whose primaries are connected, respectively, between the mains of the system and with the said conductor 16. The winding 12 in Fig. 1

and the winding composed of the coils 23 and 24 in Fig. 2 are each subject to a pressure equal to the generator-pressure minus one-half the or drop-z. e., E-- For example,ifthe dynamo-pressure is one hundred volts and the total drop over the line to the point let is ten volts then a torque will be created proportional to one hundred minus five, or ninetyfive volts, the five volts being one-half of the total drop over the lines. IVhen there is no load upon the system, a torque is exerted by each of these windings receiving current from conductor 16 proportional to the impressed pressure. As load' is put upon the system torque is created by the said windings, which varies directly as the difference between the impressed pressure and one-half the O R drop. I preferably so adjust the windings of each instrument that the winding receiving current from each conductor 16 will produce relatively twice the torque for a given pressure impressed at its terminals than that caused by the winding subject to the generator-pressure. This may be accomplished in any wellknown way, as by adjustment of the resistance 15 or by changing the number of turns of the winding. The windings of the instrument winding subject to the impressed pressure is proportional to E. The torque due to the winding receiving current from conductor the pressure at the distant point 1- I have herein shown a system of direct-current distribution and a system of alternatingcurrent distribution, and the claims relate to either.

It is obvious that changes may readily be made in the apparatus of my invention without departing from the spirit thereof, and I do not,therefore,wish to be limited to the precis construction shown; but,

Having thus described my invention, I claim as new and desire to secure by Letters Patentl. In asystem of electrical distribution, the combination with a transmission-circuit, of a voltmeter having a winding interposed between points of the circuit having unlike'differences of potential, the said winding being interposed between the sides of the circuit,

substantially as described.

2. In a system of electrical distribution, the combination with a generator, of a transmission-circuit, and a voltmeter havingawinding interposed between a pointnear the generator and a distant point of the transmission-line, the said winding being connected between points of the transmission-circuit having unlike differences of potential, the said winding being interposed between the sides of the circuit, substantially as described.

3. In a system of electrical distribution, the combination with a generator, of atransmission-circuit, and a voltmeter having one winding interposed between the generator-terminals and a second windinginterposed between points of the circuit having unlike difierences of potential, the latter Winding being interposed between the sides of the circuit, substantially as described.

4. In a system of electrical distribution, the combination with a generator, of a transmission-circuit, and a voltmeter having one winding interposed between the generator-terminals and asecond windinginterposed between .points of the circuit having unlike differences of potential, the latter winding being interposed between the sides of .the circuit, each circuit of the meter including a movable coil, said coils being mechanically coupled to jointly efiect a single measurement, substantially as described.

5. In asystem of electrical distribution, the combination with a generator, of a transmission-circuit, and a voltmeter having one winding interposed between the generator-terminals and a second windinginterposed between points of the circuit having unlike dilferences of potential, the latter winding being'interposed between the sides of the circuit,'eacl1 circuit of'the meter includingamov'ab'le coil, said coils being mechanically coupled to jointly effect a single measurement, the torques due to the said windings opposing each other, substantially as described.

6. In asystem of electrical distribution, the combination with a generator, of a transmission-circuit, a voltmeter having one winding interposed between the generator-terminals and a second winding interposed between points of the circuit having unlike difiierences ofpotential, the latter winding being interposed between the sides of the circuit, each circuit of the meter including a movable coil, said coils being mechanically coupled to jointly effect a single measurement, the torques due to the said windings opposing each other, a pointer movable with the windings, and a scale upon which the pointer may indicate measurements, substantially as described.

7. In a system of electrical distribution, the combination with a generator,'of a metallic transmission-circuit, and a voltmeter having one winding interposed between thegenorator-terminals and a second winding interposed between points of thecircuit having unlike differences of potentia1,the latter winding being interposed between the sides of the circuit, substantially as described.

8. In a system of electrical distribution, the combination with a generator, of a metallic transmission circuit, and a voltmeter having one windinginterposed betweenthe genorator-terminals and a second winding interposed between points of the circuithaving unlike difierences of potential,the latter winding being interposed between the sides of 'the circuit, each-circuit of the meter including a movable coil, said coils being mechanically coupled to jointly effect a single measurement, substantially as described.

9. In a system of electrical distribution, the combination with a generator, of a metallic transmission-circuit, and a voltmeter having one winding interposed between the generator-terminals and a second winding interposed between points of the circuit having unlike differences of potential, the latter winding being interposed between the sides of the circuit, each circuit of the meter including a movable coil, said coils being mechanically coupled to jointly effect a single measurement, the torques due to the said windings opposing each other, substantially as described.

10. In a system of electrical distribution,the combination with a generator, of a metallic transmission-circuit, a voltmeter having Zone winding interposed between the generatorterminals and a second winding interposed between points of the circuit having unlike differences of potential, the latter winding being interposed between the sides of the circuit, each circuit of the meter including a movable coil, said coils being mechanically coupled to jointly etfect a single measurement, the torques due to said windings opposing each other, a pointer movable with the windings, and a scale upon which the pointer may indicate measurements, substantially as described.

11. In asystem of electricaldistribution,the combination with a generator, of a transmission circuit, and a voltmeter having one winding interposed between the generatorterminals and a second winding interposed between a point of the circuit near the generator and asecond, distant point of the transmission-circuit, the latter winding being interposed between the sides of the circuit, substantially as described.

12. In asystem of electrical distribution,the combination with a generator, of a transmission circuit, and a voltmeter having one winding interposed between the generatorterminals and a second winding interposed between a point of the circuit near the generator-and a second distant point of the transmission-circuit, the latter winding being interposed between the sides of the circuit, each circuit of the meter including a movable coil, said coils being mechanically coupled to jointly effect a single measurement, substantially'as described.

18. In asystem of electrical distribution,the combination with a generator, of a transmission circuit, and a voltmeter having one interposed between the generator-terminals and a second winding interposed between a point of the circuit near the generator and a second, distant point of the transmission-circuit, the latter winding being interposed between the sides of the circuit, each circuit of the meter including a movable coil, said coils being mechanically coupled to jointly effect a single measurement, the torques due to the said windings opposing each other, apoiuter movable with the windings, and a scale upon which the pointer may indicate measurements, substantially as described.

In witness whereof I'hereunto subscribe my name this 20th day of December, A. D. 1899.

THOMAS DUNCAN.

Witnesses:

WILLIAM F. MEYER, JAMES W. DALTON.

sion-circuit, a voltmeter having one winding 

